//Copyright (C) 2011  Carl Rogers
//Released under MIT License
//license available in LICENSE file, or at http://www.opensource.org/licenses/mit-license.php

#include"cnpy.h"
#include<complex>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<iomanip>

char cnpy::BigEndianTest() {
	union {
		unsigned char x[2];
		short y;
	};
	x[0] = 1; x[1] = 0;
	return y == 1 ? '<' : '>';
}

char cnpy::map_type(const std::type_info& t)
{
	if(t == typeid(float) ) return 'f';
	if(t == typeid(double) ) return 'f';
	if(t == typeid(long double) ) return 'f';

	if(t == typeid(int) ) return 'i';
	if(t == typeid(char) ) return 'i';
	if(t == typeid(short) ) return 'i';
	if(t == typeid(long) ) return 'i';
	if(t == typeid(long long) ) return 'i';

	if(t == typeid(unsigned char) ) return 'u';
	if(t == typeid(unsigned short) ) return 'u';
	if(t == typeid(unsigned long) ) return 'u';
	if(t == typeid(unsigned long long) ) return 'u';
	if(t == typeid(unsigned int) ) return 'u';

	if(t == typeid(bool) ) return 'b';

	if(t == typeid(std::complex<float>) ) return 'c';
	if(t == typeid(std::complex<double>) ) return 'c';
	if(t == typeid(std::complex<long double>) ) return 'c';

	else return '?';
}

template<> std::vector<char>& cnpy::operator+=(std::vector<char>& lhs, const std::string rhs) {
	lhs.insert(lhs.end(),rhs.begin(),rhs.end());
	return lhs;
}

template<> std::vector<char>& cnpy::operator+=(std::vector<char>& lhs, const char* rhs) {
	//write in little endian
	size_t len = strlen(rhs);
	lhs.reserve(len);
	for(size_t byte = 0; byte < len; byte++) {
		lhs.push_back(rhs[byte]);
	}
	return lhs;
}

void cnpy::parse_npy_header(FILE* fp, unsigned int& word_size, unsigned int*& shape, unsigned int& ndims, bool& fortran_order) {
	char buffer[256];
	size_t res = fread(buffer,sizeof(char),11,fp);
	if(res != 11)
		throw std::runtime_error("parse_npy_header: failed fread");
	std::string header = fgets(buffer,256,fp);
	assert(header[header.size()-1] == '\n');

	size_t loc1, loc2;

	//fortran order
	loc1 = header.find("fortran_order")+16;
	fortran_order = (header.substr(loc1,5) == "True" ? true : false);

	//shape
	loc1 = header.find("(");
	loc2 = header.find(")");
	std::string str_shape = header.substr(loc1+1,loc2-loc1-1);
	if(str_shape[str_shape.size()-1] == ',') ndims = 1;
	else ndims = static_cast<unsigned int>(std::count(str_shape.begin(),str_shape.end(),',')+1);
	shape = new unsigned int[ndims];
	for(unsigned int i = 0;i < ndims;i++) {
		loc1 = str_shape.find(",");
		shape[i] = atoi(str_shape.substr(0,loc1).c_str());
		str_shape = str_shape.substr(loc1+1);
	}

	//endian, word size, data type
	//byte order code | stands for not applicable.
	//not sure when this applies except for byte array
	loc1 = header.find("descr")+9;
	bool littleEndian = (header[loc1] == '<' || header[loc1] == '|' ? true : false);
	assert(littleEndian);

	//char type = header[loc1+1];
	//assert(type == map_type(T));

	std::string str_ws = header.substr(loc1+2);
	loc2 = str_ws.find("'");
	word_size = atoi(str_ws.substr(0,loc2).c_str());
}

void cnpy::parse_zip_footer(FILE* fp, unsigned short& nrecs, unsigned int& global_header_size, unsigned int& global_header_offset)
{
	std::vector<char> footer(22);
	fseek(fp,-22,SEEK_END);
	size_t res = fread(&footer[0],sizeof(char),22,fp);
	if(res != 22)
		throw std::runtime_error("parse_zip_footer: failed fread");

	unsigned short disk_no, disk_start, nrecs_on_disk, comment_len;
	disk_no = *(unsigned short*) &footer[4];
	disk_start = *(unsigned short*) &footer[6];
	nrecs_on_disk = *(unsigned short*) &footer[8];
	nrecs = *(unsigned short*) &footer[10];
	global_header_size = *(unsigned int*) &footer[12];
	global_header_offset = *(unsigned int*) &footer[16];
	comment_len = *(unsigned short*) &footer[20];

	assert(disk_no == 0);
	assert(disk_start == 0);
	assert(nrecs_on_disk == nrecs);
	assert(comment_len == 0);
}

cnpy::NpyArray load_the_npy_file(FILE* fp) {
	unsigned int* shape;
	unsigned int ndims, word_size;
	bool fortran_order;
	cnpy::parse_npy_header(fp,word_size,shape,ndims,fortran_order);
	unsigned long long size = 1; //long long so no overflow when multiplying by word_size
	for(unsigned int i = 0;i < ndims;i++) size *= shape[i];

	cnpy::NpyArray arr;
	arr.word_size = word_size;
	arr.shape = std::vector<unsigned int>(shape,shape+ndims);
	arr.data = new char[size*word_size];
	arr.fortran_order = fortran_order;
	size_t nread = fread(arr.data,word_size,size,fp);
	if(nread != size)
		throw std::runtime_error("load_the_npy_file: failed fread");
	return arr;
}

cnpy::npz_t cnpy::npz_load(std::string fname) {
	FILE* fp = fopen(fname.c_str(),"rb");

	if(!fp) printf("npz_load: Error! Unable to open file %s!\n",fname.c_str());
	assert(fp);

	cnpy::npz_t arrays;

	while(1) {
		std::vector<char> local_header(30);
		size_t headerres = fread(&local_header[0],sizeof(char),30,fp);
		if(headerres != 30)
			throw std::runtime_error("npz_load: failed fread");

		//if we've reached the global header, stop reading
		if(local_header[2] != 0x03 || local_header[3] != 0x04) break;

		//read in the variable name
		unsigned short name_len = *(unsigned short*) &local_header[26];
		std::string varname(name_len,' ');
		size_t vname_res = fread(&varname[0],sizeof(char),name_len,fp);
		if(vname_res != name_len)
			throw std::runtime_error("npz_load: failed fread");

		//erase the lagging .npy
		varname.erase(varname.end()-4,varname.end());

		//read in the extra field
		unsigned short extra_field_len = *(unsigned short*) &local_header[28];
		if(extra_field_len > 0) {
			std::vector<char> buff(extra_field_len);
			size_t efield_res = fread(&buff[0],sizeof(char),extra_field_len,fp);
			if(efield_res != extra_field_len)
				throw std::runtime_error("npz_load: failed fread");
		}

		arrays[varname] = load_the_npy_file(fp);
	}

	fclose(fp);
	return arrays;
}

cnpy::NpyArray cnpy::npz_load(std::string fname, std::string varname) {
	FILE* fp = fopen(fname.c_str(),"rb");

	if(!fp) {
		printf("npz_load: Error! Unable to open file %s!\n",fname.c_str());
		abort();
	}

	while(1) {
		std::vector<char> local_header(30);
		size_t header_res = fread(&local_header[0],sizeof(char),30,fp);
		if(header_res != 30)
			throw std::runtime_error("npz_load: failed fread");

		//if we've reached the global header, stop reading
		if(local_header[2] != 0x03 || local_header[3] != 0x04) break;

		//read in the variable name
		unsigned short name_len = *(unsigned short*) &local_header[26];
		std::string vname(name_len,' ');
		size_t vname_res = fread(&vname[0],sizeof(char),name_len,fp);
		if(vname_res != name_len)
			throw std::runtime_error("npz_load: failed fread");
		vname.erase(vname.end()-4,vname.end()); //erase the lagging .npy

		//read in the extra field
		unsigned short extra_field_len = *(unsigned short*) &local_header[28];
		fseek(fp,extra_field_len,SEEK_CUR); //skip past the extra field

		if(vname == varname) {
			NpyArray array = load_the_npy_file(fp);
			fclose(fp);
			return array;
		}
		else {
			//skip past the data
			unsigned int size = *(unsigned int*) &local_header[22];
			fseek(fp,size,SEEK_CUR);
		}
	}

	fclose(fp);
	printf("npz_load: Error! Variable name %s not found in %s!\n",varname.c_str(),fname.c_str());
	abort();
}

cnpy::NpyArray cnpy::npy_load(std::string fname) {

	FILE* fp = fopen(fname.c_str(), "rb");

	if(!fp) {
		printf("npy_load: Error! Unable to open file %s!\n",fname.c_str());
		abort();
	}

	NpyArray arr = load_the_npy_file(fp);

	fclose(fp);
	return arr;
}
